DESCRIPTION: Glaucoma is a progressive optic neuropathy caused by a pathological loss of the retinal neurons that form the optic nerve from the eye to the brain. It is a leading cause of irreversible blindness in the United States;approximately 2.2 million people older than 40 years of age suffer from the disease and as many as 120,000 of these people are blind from glaucoma. As the population ages, the disease will become an increasingly important problem of public health, but treatment is effective in preventing or slowing vision loss and it is, therefore, important to optimize procedures for determining when treatment is needed and when it is effective. Because the cause of glaucoma is unknown, the diagnosis or progression of the disease requires ophthalmic testing to identify and quantify clinical characteristics of glaucomatous neuropathy, such as the pattern of visual field defects, anatomical changes of the optic nerve head, and thinning of the retinal nerve fiber layer. The goal of the proposed research is to gain a better understanding of the relationships between clinical measures of neural and visual losses from glaucoma. The principal experiments involve behavioral studies of visual function (standard automated perimetry) and high resolution imaging of retinal structure (optical coherence tomography) over the time course of experimental glaucoma in macaque monkeys. The data from the investigations of experimental glaucoma will be used to develop a quantitative model relating the loss of retinal neurons in a specific area of the retina to the number of axons entering the optic nerve from the same retinal area. In the final phase, the structure and function relationships that were derived from monkeys will be applied to assess the severity, or stage, of glaucoma in human patients. The research method is based on defining procedures with experimental glaucoma where there are excellent controls for the experimental and measurement variables and, then, application to human patients to test the clinical relevance and validity of the procedures. This method of going from the laboratory to the clinic should maximize the potential for significant new information about ophthalmic testing for diagnosis and assessment of glaucoma.